25. Pack Multiple Fields into a 16-bit Control Register

#include <stdio.h>
#include <stdint.h>

uint16_t pack_register(uint8_t mode, uint8_t speed, uint8_t status) {
    uint16_t reg = 0;
    if(mode > 7)mode=7;
    if(speed > 31)speed=31;
    if(status > 63)status=63;
    reg|=(mode & 0x07);
    reg|=(speed & 0x1F)<<3;
    reg|=(status & 0x3F)<<10;
    return reg;
}

int main() {
    uint8_t mode, speed, status;
    scanf("%hhu %hhu %hhu", &mode, &speed, &status);

    uint16_t reg = pack_register(mode, speed, status);
    printf("%u", reg);
    return 0;
}